The present disclosure relates to a color converting member for performing color conversion by using a phosphor, a method of manufacturing the same, a light emitting device using the color converting member, and a display device.
Previously, a liquid crystal display (LCD) is used as a thin-type display device. In the liquid crystal display, a backlight for irradiating an entire liquid crystal panel from the back side is used. According to the structure of the backlight, liquid crystal displays may be broadly divided into the direct type and the edge light type. In the edge light type, a light emitting element is provided for a side face of a light guide plate provided on the entire face of a display region. Light which is incident from the side face of the light guide plate is made propagate and, after that, is extracted from the top face of the light guide plate. On the other hand, in the direct type, for example, by disposing a plurality of light emitting elements on a substrate, plane emission is performed as a whole.
As such a backlight, there is proposed a light emitting device realizing pseudo white light by providing a phosphor layer for performing color conversion on the light outgoing side of a blue light emitting diode as a light emitting element and mixing converted color light and blue light (refer to, for example, Japanese Unexamined Patent Application Publication Nos. 2006-49657, 2004-352928, and 2007-23267.
Concretely, in Japanese Unexamined Patent Application Publication No. 2006-49657, by potting resin mixed with a YAG phosphor on a GaN-based blue light emitting diode chip, a part of blue light is converted to yellow light in the phosphor layer, thereby obtaining white light.
However, such a phosphor layer is vulnerable to oxygen and moisture in atmosphere. There is a problem such that when the phosphor layer is exposed to oxygen, moisture, and the like, it deteriorates. The color conversion efficiency of the phosphor decreases, and light emission luminance and chromaticity of the light emitting device deteriorates. Such deterioration in the phosphor is conspicuous particularly under high-temperature high-humidity environments. In Japanese Unexamined Patent Application Publication No. 2004-352928, a method of applying a phosphor layer on an exterior cap that seals a blue light emitting diode and, after that, hermetically sealing the resultant in vacuum or inert atmosphere is used. In Japanese Unexamined Patent Application Publication No. 2007-23267, a method of sealing a phosphor layer by sandwiching it between two glass substrates is proposed. However, the methods of Japanese Unexamined Patent Application Publication Nos. 2004-352928 and 2007-23267 have a problem such that the manufacturing process is complicated.
It is therefore desirable to provide a color converting member capable of suppressing deterioration in a phosphor by a simple manufacturing process, a method of manufacturing the same, and a light emitting device and a display device each using the member